The marijuana lobby likes to say that marijuana isn’t as dangerous as alcohol. Technically speaking, that may be true. But the reality of drug and alcohol use is that danger comes in many ways. The effect on driving is the biggest one.

Driving under the influence of marijuana, the most common driving-under-the-influence drug after alcohol, is dangerous. A 2012 meta-analysis in the British Medical Journal found that driving under the influence of marijuana “significantly increased risk of motor vehicle collisions compared with unimpaired driving,” and especially for fatalities. People who smoke marijuana and drive are twice as likely to cause a fatal crash compared to clean and sober people. The same study related that the risk of a car crash for people with a blood alcohol concentration of 0.8, the legal limit, is about 2.7 times higher than for a sober driver. So, not a whole lot of difference.

Drugs other than alcohol are increasingly found in injured and fatally injured drivers

In some jurisdictions, marijuana has surpassed alcohol in DUIs among young people

And, just like with alcohol or any other drug, the more pot you smoke, or the stronger the weed, the more likely you are to crash your car.

Drugged driving poses a widening threat. The reality of getting high is that many people use drugs and alcohol together. Drinking beer and smoking weed is very commonplace partying. And it’s particularly dangerous for driving. A study about combined alcohol and marijuana use and driving found that the two used together caused severe impairment for driving, particularly in slowed reaction time.

A 2012 study in California showed that twice as many weekend nighttime drivers test positive for drugs, with as many using marijuana as alcohol. A national survey in 2007 showed that weekend night-time drivers in the United States were seven times more likely to be using drugs compared to alcohol. In general, research shows that the percentage of fatally injured drivers who test positive for drugs is going up.

Determining the level of drug use that causes impairment, or that compares to illegal blood alcohol concentrations, has proven very difficult. So, some States (Arizona, Delaware, Georgia, Indiana, Illinois, Iowa, Michigan, Minnesota, Nevada, North Carolina, Ohio, Pennsylvania, Rhode Island, South Dakota, Utah, Virginia, and Wisconsin) have passed “per se” laws: It’s illegal to drive if there is any detectable drug level in the driver’s blood.

With the legalization of marijuana, more people will be smoking marijuana, so drugged driving will likely increase. The marijuana lobby likes to suggest that more people smoking weed will mean fewer people drinking – therefore, less drunk driving. But researchers say there’s no evidence of that. So, we will probably have an increase in drugged driving while drinking and driving remains the same. If so, it follows that drinking and drugging while driving may increase. That’s not a good situation, to put it mildly.

5 Responses to Legalization may mean more drugged driving — and more drunk-drugged driving

Great article Jim.
A maximum BAC of 0.08 for drivers is way too high. In Australia we have a maximum BAC of 0.05 and we have folks lobbying for a reduction of this limit to 0.02.
It’s arguable to risk your own life and limbs on some kind of risk taking endeavour, but take it upon yourself to multiply your risk of accident by a factor of nearly three is outrageous.
We also have industrialized the process of testing for both alcohol limits as well as weed. A positive reading for THC and methamphetamine is enough to lose your licence for some considerable time.
Our Media is flooded with warning messages and I’d expect to be pulled over – along with 10 other cars at a time – at any time – day or night – at least once a year. Friends report up to 3 times per year.
Chances of driving undetected for drugs including alcohol in Australia – and getting away with it? Zero.

Jim, thanks for your response.
We have a major problem with “drink-walking” or organized, commercialized, binge drinking.
This was done via a criminal-level policy of making alcohol available anywhere at anytime. A moronic thing to do for an addictive drug that is toxic, carcinogenic and teratogenic*.
We do somethings really well and I believe we ought to examine and publicize to our constituencies what works and what doesn’t – elsewhere in the world. It’s an old method but a good one!

This (plain packaging) works:
Shopkeepers have to hide from plain view cigarettes.
Just because it’s legal doesn’t mean you can’t minimize the uptake without effective regulation.

* Teratogenic. Watch out for forthcoming research will show that Fifty Percent (50%) of an indigenous population under the age of 8 years have been hit by FASD. At the same time some local politicians are endeavouring to lift community imposed restrictions on the availabilty of alcohol to these defenceless and blighted communities.
I’ve never heard of such a distressing toll in all the world… maybe others have?

We will learn like others before us that legalizing marijuana use is the wrong thing to do. Most alcohol users like myself have a drink once in a while because we like the taste or as a light social lubricant, while individuals smoke THC to get high. This will become a bigger and bigger problem in this country.

RE: “A study about combined alcohol and marijuana use and driving found that the two used together caused severe impairment for driving, particularly in slowed reaction”
Two items come to mind when I read this. First alcohol opens the blood brain barrier that protects the brain from many toxic substances, thus opening the gate for marijuana (and any other substance) in the bloodstream to enter the brain. Second, marijuana reduces nausea and the vomiting response that make it easier to ingest larger quantities of alcohol before the body’s natural response (which is hindered by the mj) tells us it’s time to quit. This could increase the risk of alcohol poisoning and lead to drivers who may have higher BAC’s. Bad combo.